The field of the present invention is damping systems for torque variations in a drive train.
Torque damping devices have been employed to reduce shock loading within a drive train. One such prior device is illustrated in FIG. 1. An output shaft from an engine or transmission is coupled to a drive shaft by means of a drive member. The drive member may be splined to the drive shaft such that it can move axially relative thereto. The splines require the rotation of the drive member with the drive shaft. The drive member is also coupled to the output shaft of the engine or transmission by means of a cam coupling mechanism. Such a mechanism includes cam followers fixed to one or the other of the output shaft and drive member. A cam is fixed to the other of these drive elements and has a radially extending cam surface upon which the follower rides. With increased or decreased torque loading, relative rotation between the output shaft and the drive member is allowed through a relatively small angle for relieving transitory loads. As the output shaft and the drive member experience some relative angular rotation, the drive member is also moved axially against a bias spring.
Also associated with such damping systems have been fluid damping cylinders. In such a system, a concentrically arranged piston and sleeve may be employed to define an oil chamber on either side of the piston. An orifice extends through the piston to allow for damping flow between chambers. One of the piston and sleeve is fixed to the drive member while the other is fixed to the drive shaft. Through such an arrangement, some relative rotation is provided between elements of the drive train. This relative rotation is resisted by both a bias spring member and by fluid damping. Torque peaks or shock may thus be reduced within the drive train by such spring loading and damped relative rotation of the drive components.
In two-wheeled vehicles and the like which have incorporated such systems, the power train is generally required to be very compact. The foregoing device, illustrated in FIG. 1, requires some axial space to accommodate both oil chambers arranged in series along the mechanism. Consequently, on compact drive systems, such a mechanism may be difficult to include. Additionally, such mechanisms tend to employ the same oil between servicing. The damping action to which such oil is subjected can lead to oil overheating which may result in fluid deterioration.